Fix /etc/tcb/*/shadow* permissions

Looks like there's some issue with fakeroot as pseudousers
created with useradd during package installation have their
/etc/tcb/*/shadow files with proper permissions ($user:auth)
but shadow- and shadow.lock belong to root:root which makes
passwd(1) fail.

image.in/image-scripts.d/09-tcb-fix

@@ -0,0 +1,8 @@
+#!/bin/sh -e
+# /etc/tcb/<user>/shadow* permissions can be wrong
+# if an account was created from installed package
+
+cd /etc/tcb
+for u in *; do
+	chown "$u":auth "$u"/shadow*
+done